Rolling bearing

ABSTRACT

A rolling bearing includes: a first raceway member having a first annular raceway surface; a second raceway member having a second annular raceway surface opposing the first raceway surface; a plurality of rolling elements arranged between the first raceway surface and the second raceway surface so as to roll; and a guide member formed integrally with or separately from the second raceway surface. The guide member including: an annular guide surface arranged at a position different form the second raceway surface in an axial direction; a plurality of flow paths which are separately provided in the axial direction and in which compressed air for supplying lubricating oil flows; and discharge openings which spray the compressed air to a guided surface. An annular cage that holds the plurality of rolling elements at given intervals in a circumferential direction and has the guided surface which opposes the guide surface such that the guided surface can slidably contact the guide surface.

The present Application is a Divisional Application of U.S. patentapplication Ser. No. 12/998,219, filed on Mar. 28, 2011, which is basedon and claims priority to Japanese Patent Application No. 2008-258504,filed on Oct. 3, 2008 and to Japanese Patent Application No.2008-258522, filed Oct. 3, 2008, and which claims priority toInternational Application No. PCT/JP2009/067243, filed on Oct. 3, 2008,the entire contents of each of which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates to a rolling bearing, and moreparticularly to a rolling bearing of a type which sprays compressed airof an oil/air lubrication system to a part between a cage and a guidesurface thereof.

BACKGROUND ART

Generally, a rolling bearing such as a cylindrical roller bearingincludes: an outer ring; an inner ring concentrically arranged insidethe outer ring in a radial direction; a plurality of rolling elementsarranged between the outer ring and the inner ring so as to roll; and acage for holding circumferential intervals of the plurality of rollingelements. Further, as a guide system of the cage of the rolling bearing,three guide systems are known, which include an outer ring guide, aninner ring guide and a rolling element guide.

In the rolling element guide of the above-described guide systems, aheat generation or seizure is likely to occur in a pocket of the cagedue to: a runout of the cage caused by a centrifugal force generatedduring a high speed rotation; an increase in a surface pressure by aload received from the rolling elements and a shortage of lubrication ona slide surface. Thus, the rolling element guide is disadvantageous inview of durability. As compared therewith, since the outer ring guide orthe inner ring guide (hereinafter refer to as a bearing ring guide) hasa higher abrasion resistance performance during the high speed rotationthan the rolling element guide, the bearing ring guide can be preferablyused, for example, for supporting a main spindle of a machine tool.However, even in the bearing ring guide, the abrasion resistanceperformance is desired to be more improved. Here, in order to morereduce an abrasion due to a contact of the cage and a bearing ring,lubrication between both the members is requested to be properlymaintained. Especially, it is effective to suppress the abrasion in aposition where the abrasion is likely to occur.

Further, a radial position of the cage is requested to be stabilized sothat the cage is not inclined.

A below-described Patent Document 1 discloses that lubricating oil issupplied to a part between a cage and an outer ring so as to prevent anabrasion or seizure due to a contact of both the members.

Further, the below-described Patent Document 1 discloses that compressedair is discharged from supply holes formed in the outer ring at bothsides of a rolling element in the axial direction and the lubricatingoil fed by the compressed air is supplied to the part between the cageand the outer ring to prevent the abrasion or seizure due to the contactof both the members. In this technique, the compressed air is sprayed toboth the sides of the cage in the axial direction so that the cage maybe hardly inclined, however, a rolling bearing of a type is notparticularly considered that only one side of a cage in the axialdirection is guided by a bearing ring.

RELATED ART DOCUMENTS Patent Documents

-   Patent Document 1: JP-A-5-60145

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

An object of the present invention is to provide a rolling bearingcapable of properly maintaining lubrication between a cage and a guidesurface and suppress an abrasion in a position where the abrasion isespecially likely to occur.

Further, an object of the present invention is to provide a rollingbearing of a type that only one side of a cage in the axial direction isguided by a bearing ring in which lubrication between the cage and aguide surface can be properly maintained, a radial position of the cagecan be stabilized, and an abrasion or seizure of the cage can bepreferably prevented.

Means for Solving the Problem

According to a first aspect of the present invention, a rolling bearingof the present invention includes: a first raceway member having a firstannular raceway surface; a second raceway member having a second annularraceway surface opposing the first raceway surface; a plurality ofrolling elements arranged between the first raceway surface and thesecond raceway surface so as to roll; a guide member formed integrallywith or separately from the second raceway surface, the guide memberincluding: an annular guide surface arranged at a position differentfrom the second raceway surface in an axial direction; a flow path inwhich compressed air for supplying lubricating oil flows; and an annulargroove provided in the guide surface in a circumferential direction andhaving a discharge opening connected to the flow path in a groove bottompart and an introducing surface configured to introduce the compressedair toward the second raceway member in the axial direction; and anannular cage that holds the plurality of rolling elements at givenintervals in the circumferential direction and has a guided surfacewhich opposes the guide surface such that the guided surface canslidably contact the guide surface.

According to the above-described structure, when the compressed air forsupplying the lubricating oil of an oil/air lubrication system isdischarged from the discharge opening of the flow path, the compressedair is guided so as to flow to an inner side in the axial direction bythe introducing surface of the annular groove. When the guided surfaceof the cage contacts an inner side end edge (for instance, a part shownby reference numeral 15 e in FIG. 1) of the guide surface in the axialdirection, an abrasion is likely to occur in the contact part. However,in the present invention, since the guided surface of the cage hardlycontacts the inner side end edge of the guide surface in the axialdirection by the pressure of the compressed air introduced to the innerside in the axial direction, and the lubricating oil can be positivelysupplied to the part, a local abrasion of the cage in this part can besuppressed.

In the above-described structure, the introducing surface may include aside wall surface arranged in an inner side of the annular groove in theaxial direction or side wall surfaces at both sides in the axialdirection. In both cases, the side wall surface is preferably formed asan inclined surface which is inclined toward the inner side in the axialdirection from a groove bottom side to an opening side of the annulargroove. Further, when an inferior angle formed by the side wall surfacearranged in the inner side of the annular groove in the axial directionand the guide surface is α, and an inferior angle formed by the sidewall surface arranged in the outer side in the axial direction and theguide surface is β, a relation expressed by β<α is preferably set. Thus,the compressed air discharged from the discharge opening can bepreferably introduced to the inner side in the axial direction.

The guide member preferably includes a spacer arranged to be adjacent tothe second raceway member. Since the spacer is a member separated fromthe second raceway member, the spacer may be made of a material high inits heat radiation which is different from that of the second racewaymember or the volume (mass) of the spacer may be increased more thanthat of the second raceway member to improve the heat radiation. Thus,the rise of temperature of the guide member due to the contact with thecage can be suppressed and the seizure can be prevented.

According to a second aspect of the present invention, a rolling bearingof the present invention includes: a first raceway member having a firstannular raceway surface; a second raceway member having a second annularraceway surface opposing the first raceway surface; a plurality ofrolling elements arranged between the first raceway surface and thesecond raceway surface so as to roll; a guide member formed integrallywith or separately from the second raceway surface, the guide memberincluding: an annular guide surface arranged at a position differentform the second raceway surface in an axial direction; a plurality offlow paths which are separately provided in the axial direction and inwhich compressed air for supplying lubricating oil flows; and dischargeopenings which spray the compressed air to a guided surface; and anannular cage that holds the plurality of rolling elements at givenintervals in a circumferential direction and has the guided surfacewhich opposes the guide surface such that the guided surface canslidably contact the guide surface.

According to the above-described structure, when the compressed air forsupplying the lubricating oil of the oil/air lubrication system isdischarged from the plurality of discharge openings formed to beseparated in the axial direction and sprayed to the guided surface ofthe cage. Since the lubricating oil fed by the compressed air issupplied to a part between the guide surface and the guided surface, anabrasion or seizure due to the contact of the guide surface and theguided surface can be suppressed. Then, since the compressed air issprayed to a plurality of positions separated in the axial directionrelative to the guided surface of the cage, the cage is hardly inclinedin the radial direction and a position of the cage can be stabilizedwith respect to the radial direction.

Preferably, in the above-described structure, the discharge openings arearranged in a plurality of rows in the axial direction such that in eachof rows, the discharge openings are formed at plurality of positions inthe circumferential direction, and a total amount of discharge of thecompressed air from the discharge openings in each row is set to belarger in the row closer to the inner side in the axial direction.According to this structure, the compressed air is more discharged fromthe discharge openings of the row in the inner side in the axialdirection (the rolling element side), so that an inner side part of theguided surface of the cage in the axial direction can be more stronglysupported. Accordingly, the guided surface can be restrained fromcontacting an inner, side end edge (for example, a part shown byreference numeral 15 e in FIG. 1) of the guide surface in the axialdirection, and the cage can be prevented from being locally abraded inthe contact part.

Further, a total opening area of the discharge openings in each row canbe set so as to be larger in the row closer to the inner side in theaxial direction. Thus, the total amount of discharge can be moreincreased in the row the closer to the inner side in the axial directionby a simple structure.

The guide member is preferably a spacer arranged adjacent to the secondraceway member. Thus, since the spacer is a member separated from thesecond raceway member, the spacer may be formed with a material high inits heat radiation which is different from that of the second racewaymember or the volume (mass) may be more increased than that of thesecond raceway member to improve the heat radiation. Thus, the rise oftemperature of the guide member due to a contact with the cage can besuppressed and seizure can be prevented.

Advantages of the Invention

According to the present invention, the lubrication between the cage andthe guide surface can be properly maintained, and an abrasion can besuppressed in a position where the abrasion is especially likely tooccur.

Further, the radial position of the cage can be stabilized and theabrasion or seizure of the cage can be preferably prevented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a rolling bearing according to a firstexemplary embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the rollingbearing according to the first exemplary embodiment.

FIG. 3 is a sectional view of a main part of a rolling bearing accordingto a second exemplary embodiment.

FIG. 4 is a sectional view of a rolling bearing according to a thirdexemplary embodiment of the present invention.

FIG. 5 is an enlarged sectional view of a main part of the rollingbearing according to the third exemplary embodiment.

MODE FOR CARRYING OUT THE INVENTION First Exemplary Embodiment

FIG. 1 is a sectional view of a rolling bearing 10 according to a firstexemplary embodiment of the present invention. The rolling bearing 10includes an annular outer ring (a second raceway member) 11, an innerring (a first raceway member) 12 concentrically arrange in an innerperipheral side of the outer ring 11, a plurality of cylindrical rollers13 as rolling elements arranged between the outer ring 11 and the innerring 12 and a cage 14 for holding the cylindrical rollers 13 atprescribed intervals in the circumferential direction. In abelow-described explanation, an axially outward (outside in the axialdirection) direction means a direction directed toward both sides in theaxial direction from a central part of the cylindrical roller bearing 10in the axial direction (a center of a roller in the axial direction). Anaxially inward direction (inside in the axial direction) means adirection directed toward a central part in the axial direction fromboth sides of the cylindrical roller bearing 10 in the axial direction.

The outer ring 11 is a member formed in an annular shape by using alloysteel such as bearing steel. On an inner peripheral surface of the outerring, an outer ring raceway surface 11 a on which the cylindricalrollers 13 roll is formed along the circumferential direction.

The inner ring 12 is also a member formed in an annular shape by usingthe alloy steel such as the bearing steel. On an outer peripheralsurface of the inner ring, an inner ring raceway surface 12 a on whichthe cylindrical rollers 13 roll is formed so as to oppose the outer ringraceway surface 11 a. Further, on the outer peripheral surface of theinner ring 12, an inner ring collar part 12 b is formed that protrudesradially outward at both sides of the inner ring raceway surface 12 a inthe axial direction. By this inner ring collar part 12 b, the axialmovement of the cylindrical rollers 13 is regulated.

The plurality of cylindrical rollers 13 can roll on the outer ringraceway surface 11 a and the inner ring raceway surface 12 a. Thus, theouter ring 11 and the inner ring 12 are rotatable relative to eachother.

The outer ring 11 has an axial length smaller than that of the innerring 12. At one end in the axial direction (a right end in FIG. 1), theaxial position of the outer ring corresponds to the axial position ofthe inner ring 12. However, the other end of the outer ring (a left end)is retracted from the inner ring 12 in the axial direction. On a leftside of the outer ring 11 in the axial direction, an outer spacer 15 isprovided adjacent thereto, and the axial position of the outer ring 11is set by the outer spacer 15. Further, on a left side of the inner ring12 in the axial direction, an inner spacer 16 is provided adjacentthereto and the axial position of the inner ring 12 is set by the innerspacer 16. The outer ring 11, the inner ring 12 and the spacers 15 and16 may be respectively arranged in opposite sides of the right and leftsides.

The outer spacer 15 has a large inner diameter at a part 15 a adjacentto the outer ring 11 in the axial direction, and has a small innerdiameter at a part 15 b separated from the outer ring 11 in the axialdirection. The part 15 b is arranged outside the cage 14 in the axialdirection (a left side in FIG. 1). An inner peripheral surface of thepart 15 b comes close to an outer peripheral surface of the inner spacer16. An inner peripheral surface 21 of the part 15 a adjacent to theouter ring 11 is arranged slightly inside the outer ring raceway surface11 a in the radial direction (the inner ring 12 side).

The cage 14 is a cylindrical member formed by using a synthetic resinsuch as a phenol resin and includes a plurality of pockets 14 a thatrespectively accommodate and hold the plurality of cylindrical rollers13 at prescribed intervals in the circumferential direction. The cage 14is arranged between the outer ring 11 and the inner ring 12 so as to besubstantially concentric with both the rings 11 and 12. One end of thecage 14 in the axial direction (the left side in FIG. 1) protrudesoutward from the outer ring 11 in the axial direction. On an outerperipheral surface thereof, a guided surface 22 is provided so as tooppose the inner peripheral surface (a guide surface) 21 of the part 15a of the outer spacer 15 such that the guided surface 22 can slidablycontact the inner peripheral surface 21.

When the outer ring 11 and the inner ring 12 are rotated relatively toeach other to rotate the cage 14 and the outer spacer 15 relatively toeach other, the guided surface 22 of the cage 14 slidably contacts theguide surface 21 of the outer spacer 15. Thus, the cage 14 is guided bythe guide surface 21 so that the center of rotation of itself issubstantially the same as the centers of rotation of the outer ring 11and the inner ring 12. Accordingly, the outer spacer 15 functions as aguide member for guiding the rotation of the cage 14.

In the outer spacer 15, flow paths 17 a to 17 d are formed for supplyinglubricating oil to the cylindrical roller bearing 10. The flow paths 17a to 17 d include the peripheral groove 17 a formed on an outerperipheral surface of the outer spacer 15 along the circumferentialdirection, a first flow path 17 b formed inward from a bottom part ofthe peripheral groove 17 a in the radial direction in the part 15 b ofthe outer spacer 15, a second flow path 17 c formed inward from thebottom part of the peripheral groove 17 a in the radial direction andopened in the guide surface 21 in the part 15 a closer to the outer ring11 side than to the first flow path 17 b and a third flow path 17 dformed toward a part between the inner ring 12 and the cage 14 from aninner end part of the first flow path 17 b in the radial direction. Thefirst flow path 17 b, the second flow path 17 c and the third flow path17 d are formed at a plurality of positions (preferably, three or morepositions) in the circumferential direction of the outer spacer 15.

To the flow paths 17 a to 17 d, the lubricating oil is supplied from alubricating unit not shown in the drawing. As the lubricating unit, anoil/air lubrication system is used that supplies the lubricating oillittle by little by compressed air. The lubricating oil is supplied to apart between the cage 14 and the inner ring 12 through the first flowpath 17 b and the third flow path 17 d from the peripheral groove 17 ato lubricate a part between the inner ring 12 and the cylindrical roller13. Further, the lubricating unit supplies the lubricating oil to a part(a part between the guide surface 21 and the guided surface 22) betweenthe outer spacer 15 and the cage 14 through the second flow path 17 cfrom the peripheral groove 17 a to mainly lubricate the part betweenthem.

FIG. 2 is a sectional view showing a main part (the part of the guidesurface 21 and the guided surface 22) which is enlarged of thecylindrical roller bearing 10. The second flow path 17 c has a dischargeopening 17 c 1 arranged so as to be opened in a groove bottom part of anannular groove 31 formed in the guide surface 21.

The annular groove 31 is formed along the circumferential direction ofthe guide surface 21 and a sectional form passing an axis of thecylindrical roller bearing 10 is substantially trapezoid. The annulargroove 31 has an opening width in the axial direction formed to belarger than a diameter of the second flow path 17 c (a diameter of thedischarge opening 17 c 1) Ø and includes one pair of side wall surfaces31 a 1 and 31 a 2 inclined in opposite directions to each other so thata width is gradually larger to the opening side from the groove bottomside. A bottom surface 31 b between the one pair of side wall surfaces31 a 1 and 31 a 2 is a surface parallel to the guide surface 21 and hasan axial width substantially the same as or slightly larger than thediameter Ø of the discharge opening 17 c 1 of the second flow path 17 c.

The side wall surface 31 a 1 of an inner side (a right side in FIG. 2)of the annular groove 31 in the axial direction is formed as an inclinedsurface which is inclined inward in the axial direction as it goesinward in the radial direction. As compared therewith, the side wallsurface 31 a 2 of an outer side (a left side in FIG. 2) of the annulargroove 31 in the axial direction is formed as an inclined surface whichis inclined outward in the axial direction as it goes inward in theradial direction. An inferior angle α formed by the side wall surface 31a 1 of the inner side in the axial direction and the guide surface 21and an inferior angle β formed by the side wall surface 31 a 2 of theouter side in the axial direction and the guide surface 21 satisfybelow-described conditions (a) to (c).π/2<α<π  (a)π/2<β<π  (b)β<α  (c)

The compressed air passing through the second flow path 17 c isdischarged from the discharge opening 17 c 1 and sprayed to the guidedsurfaced 22 through the annular groove 31. At this time, the compressedair is introduced to the inner side in the axial direction and to theouter side in the axial direction (see arrow marks a and b in FIG. 1) bythe inclinations of the one pair of side wall surfaces 31 a 1 and 31 a 2of the annular groove 31 and supplied to the part between the guidesurface 21 and the guided surface 22 to supply the lubricating oil tothe part between them.

Since the side wall surface 31 a 1 of the inner side of the annulargroove 31 in the axial direction is more greatly inclined (β<α) than theside wall surface 31 a 2 of the outer side in the axial direction, thecompressed air is supplied more to the inner side in the axial directionthan to the outer side in the axial direction from the discharge opening17 c 1. In such a way, by the pressure of a large amount of compressedair supplied to the inner side in the axial direction, as shown in FIG.1, the guided surface 22 of the cage 14 hardly contacts an innerperipheral corner part (an inner side end edge of the guide surface 21in the axial direction) 15 e of the outer spacer 15 of the outer ring 11side. Thus, the cage 14 can be restrained from being locally abraded inthis part 15 e. Further, since an amount of supply of the lubricatingoil is increased by the large amount of compressed air supplied to theinner side in the axial direction from the discharge opening 17 c 1, theabrasion of the cage 14 in the part 15 e can be more suppressed and thelubricating oil can be also positively supplied to a part between thecylindrical roller 13 and the outer ring raceway surface 11 a.

Further, since the compressed air is discharged from the dischargeopening 17 c 1 so that a contact surface pressure of the guide surface21 and the guided surface 22 is lowered, a rotating resistance of thecage 14 can be reduced and an abrasion or seizure due to a contact ofthe guide surface 21 and the guided surface 22 can be suppressed.

Since the guide surface 21 that guides the cage 14 is formed in theouter spacer 15 separated from the outer ring 11, the outer spacer 15may be made of a material high in its heat radiation which is differentfrom that of the outer ring 11 or the volume (mass) of the outer spacer15 may be increased to improve the heat radiation. In such a way, theheat radiation of the outer spacer 15 is improved, so that the rise oftemperature of the outer spacer 15 due to the contact with the cage 14can be suppressed and the seizure of the cage 14 can be prevented.

Since the guide surface 21 formed in the outer spacer 15 is arrangedinside the outer ring raceway surface 11 a in the radial direction,namely, in the inner ring 12 side (in the inner ring raceway surface 12a side), the guide surface 21 can be allowed to come close to the guidedsurface 22 of the cage 14 and can guide the cage 14 without forming theguided surface 22 of the cage 14 in such a special configuration as tolargely protrude outward in the radial direction.

Second Exemplary Embodiment

FIG. 3 is an enlarged sectional view of a main part of a rolling bearingaccording to a second exemplary embodiment of the present invention. Thepresent exemplary embodiment is different from the first exemplaryembodiment in view of a point that an inferior angle 13 formed by a sidewall surface 31 a 2 of an outer side of an annular groove 31 in theaxial direction and a guide surface 21 is smaller than 90° (smaller thanπ/2). Further, the side wall surface 31 a 2 of the outer side in theaxial direction has a degree of inclination to an inner side in theaxial direction smaller than that of a side wall surface 31 a 1 of aninner side in the axial direction. Namely, in the present exemplaryembodiment, an inferior angle α formed by the side wall surface 31 a 1of the inner side in the axial direction and the guide surface 21 and aninferior angle β formed by the side wall surface 31 a 2 of the outerside in the axial direction and the guide surface 21 satisfybelow-described conditions (d) to (f).π/2<α<π  (d)0<β<π/2  (e)(π/2−β)<(α−π/2)  (f)

In the present exemplary embodiment, the side wall surface 31 a 2 of theouter side in the axial direction functions as an introducing surfacefor introducing compressed air to the inner side in the axial direction(see an arrow mark b′). Thus, operational effects of the first exemplaryembodiment can be more improved.

The present invention is not limited to the above-described exemplaryembodiments respectively and a design may be suitably changed. Forinstance, a guide surface 21 may be formed in an outer ring 11. In thiscase, a collar part may be formed for regulating an axial movement of acylindrical roller 13 in an inner peripheral part of the outer ring 11and an inner peripheral surface of the collar part may be used as theguide surface 21.

Further, in the exemplary embodiments respectively, the second flow path17 c, the guided surface 22, the guide surface 21 and the annular groove31 may be provided at both sides in the axial direction with thecylindrical roller 13 sandwiched between them. However, the presentinvention is very advantageous to prevent the guided surface 22 of thecage 14 from contacting the inner side end edge 15 e of the guidesurface 21 in the axial direction in the cylindrical roller bearing 10having the second flow path 17 c, the guided surface 22 and the guidesurface 21 provided only in one side in the axial direction.

The present invention may be applied to a rolling bearing in which aguide form of a cage is a guide form by an inner ring. Further, thepresent invention may be applied to other rolling bearings than acylindrical roller bearing such as a ball bearing, a needle shapedroller bearing and a tapered roller bearing. Further, in the exemplaryembodiments respectively, as the lubricating unit, the oil/airlubrication system is exemplified. However, the present invention mayemploy any lubrication system that supplies lubricating oil by usingcompressed air without a special limitation. For instance, otherlubrication system such as an oil/mist lubrication system may beemployed that supplies mist type lubricating oil by compressed air.

Third Exemplary Embodiment

FIG. 4 is a sectional view of a third exemplary embodiment of thepresent invention. FIG. 5 is a sectional view showing that a main part(a part of a guide surface 21 and a guided surface 22) of a rollingbearing of the present exemplary embodiment is enlarged. In FIG. 4 andFIG. 5, the same members as those of FIG. 1 and FIG. 2 are designated bythe same reference numerals an explanation of them will be omitted.

To flow paths 17 a to 17 d and 27 c 1 and 27 c 2, lubricating oil issupplied from a lubricating unit not shown in the drawing. As thelubricating unit, an oil/air lubrication system is used that suppliesthe lubricating oil little by little by compressed air. The lubricatingunit sprays the compressed air to a part between a cage 14 and an innerring 12 through the first flow path 17 b and the third flow path 17 dfrom the peripheral groove 17 a to supply the lubricating oil andlubricate a part between the inner ring 12 and a cylindrical roller 13.Further, the lubricating unit sprays the compressed air to a part (apart between the guide surface 21 and the guided surface 22) between anouter spacer 15 and the cage 14 through the second flow paths 27 c 1 and27 c 2 from the peripheral groove 17 a to supply the lubricating oil andmainly lubricate the part between them.

In the present exemplary embodiment, in the outer spacer 15, the secondflow paths 27 c 1 and 27 c 2 opened in the guide surface 21 areprovided. In the second flow paths 27 c 1 and 27 c 2, discharge openings27 c 1′ and 27 c 2′ are arranged so as to oppose the guided surface 22.

In the present exemplary embodiment, the two second flow paths 27 c 1and 27 c 2 are arranged in parallel in the axial direction on aprescribed section passing an axis of a cylindrical roller bearing 10.Further, in an entire circumference of the cylindrical roller bearing10, a plurality of second flow paths 27 c 1 and 27 c 2 are formedrespectively in the arrangements of two rows in the axial direction.

When the second flow paths 27 c 1 and 27 c 2 are arranged in the tworows in the axial direction as described above, the compressed airdischarged respectively from the discharge openings 27 c 1′ and 27 c 2′of the second flow paths 27 c 1 and 27 c 2 is sprayed to the guidedsurface 22, so that the retained 14 can be supported at two positions inthe axial direction. Thus, the cage 14 is hardly inclined in the radialdirection and a position of the cage 14 can be stabilized with respectto the radial direction. Further, when the compressed air is sprayed tothe guided surface 22, a contact surface pressure of the guide surface21 and the guided surface 22 can be lowered, a rotating resistance ofthe cage 14 can be reduced and an abrasion or seizure due to the contactof the guide surface 21 and the guided surface 22 can be suppressed.

A diameter (a diameter of the discharge opening 27 c 2′) Ø2 of eachsecond flow path 27 c 2 of the row in an inner side (a right side inFIG. 5; the cylindrical roller 13 side) of the cylindrical rollerbearing 10 in the axial direction is larger than a diameter (a diameterof the discharge opening 27 c 1′) Ø1 of each second flow path 27 c 1 ofthe row of an outer side (a left side in FIG. 5) in the axial direction.Accordingly, a total opening area of the discharge opening 27 c 2′ ofthe second flow path 27 c 2 of the row of the inner side in the axialdirection is larger than a total opening area of the discharge opening27 c 1′ of the second flow path 27 c 1 of the row of the outer side inthe axial direction. A total amount of discharge of the compressed airdischarged from the second flow path 27 c 2 of the row of the inner sidein the axial direction is larger than a total amount of discharge of thecompressed air discharged from the second flow path 27 c 1 of the row ofthe outer side in the axial direction. Therefore, the cage 14 is morestrongly supported by the compressed air discharged from the second flowpath 27 c 2 of the row of the inner side in the axial direction.

Accordingly, the guided surface 22 of the cage 14 can be prevented fromcontacting an inner peripheral corner part (an inner side end edge ofthe guide surface 21 in the axial direction) 15 e (see FIG. 4) of theouter spacer 15 of an outer ring 11 side, and the retained 14 can beprevented from being locally abraded in this part.

The present invention is not limited to the above-described exemplaryembodiments respectively and a design may be suitably changed. Forinstance, a guide surface 21 may be formed in an outer ring 11. In thiscase, a collar part may be formed for regulating an axial movement of acylindrical roller 13 in an inner peripheral part of the outer ring 11and an inner peripheral surface of the collar part may be used as theguide surface 21. Further, in the exemplary embodiments, a flow rate ofthe compressed air supplied respectively to the second flow paths 27 c 1and 27 c 2 of the rows may be changed by a flow rate control valve.Further, in the above-described embodiments, as the second flow path inwhich the compressed air flows, three or more rows of second flow pathsmay be formed in the axial direction.

The present invention may be applied to a rolling bearing in which aguide form of a cage is a guide form by an inner ring. Further, thepresent invention may be applied to other rolling bearings than acylindrical roller bearing such as a ball bearing, a needle shapedroller bearing and a tapered roller bearing. Further, in the exemplaryembodiments respectively, as the lubricating unit, the oil/airlubrication system is exemplified. However, the present invention mayemploy any lubrication system that supplies lubricating oil by usingcompressed air without a special limitation. For instance, otherlubrication system such as an oil/mist lubrication system may beemployed that supplies mist type lubricating oil by compressed air.

DESCRIPTION OF REFERENCE NUMERALS

-   -   10 cylindrical roller bearing    -   11 outer ring    -   12 inner ring    -   13 cylindrical roller    -   14 cage    -   15 outer spacer    -   17 c flow path    -   17 c 1 discharge opening    -   27 c 1 flow path (narrow width)    -   27 c 2 flow path (wide width)    -   21 guide surface    -   22 guided surface    -   31 annular groove    -   31 a 1 side wall surface of inner side in axial direction        (introducing surface)    -   31 a 2 side wall surface of outer side in axial direction        (introducing surface)

The invention claimed is:
 1. A rolling bearing includes: a first racewaymember having a first annular raceway surface; a second raceway memberhaving a second annular raceway surface opposing the first racewaysurface; a plurality of rolling elements arranged between the firstraceway surface and the second raceway surface so as to roll; a guidemember formed integrally with or separately from the second racewaysurface, the guide member including: an annular guide surface arrangedat a position different form the second raceway surface in an axialdirection; a plurality of flow paths which are separately provided inthe axial direction and in which compressed air for supplyinglubricating oil flows; and discharge openings which spray the compressedair to a guided surface; and an annular cage that holds the plurality ofrolling elements at given intervals in a circumferential direction andhas the guided surface which opposes the guide surface such that theguided surface can slidably contact the guide surface.
 2. The rollingbearing according to claim 1, wherein the guide member comprises aspacer arranged to be adjacent to the second raceway member.
 3. Therolling bearing according to claim 1, wherein the discharge openings arearranged in a plurality of rows in the axial direction such that in eachof rows, the discharge openings are formed at plurality of positions inthe circumferential direction, and wherein a total amount of dischargeof the compressed air from the discharge openings in each row is set tobe larger in the row closer to the inner side in the axial direction. 4.The rolling bearing according to claim 3, wherein the guide membercomprises a spacer arranged to be adjacent to the second raceway member.5. The rolling bearing according to claim 3, wherein a total openingarea of the discharge openings in each row is set so as to be larger inthe row closer to the inner side in the axial direction.
 6. The rollingbearing according to claim 5, wherein the guide member comprises aspacer arranged to be adjacent to the second raceway member.